Before we go any further, let me just explain that this blog will be longer than usual, because Diagnosis Murder is, without any trace of competition, my favourite detective show of all time, bar none, ever. I like it so much that the theme music (by the ever-excellent Dick DeBenedictis – imagine being responsible for the themes of Diagnosis Murder and Perry Mason, and not being an actual saint. Weird) is the ringtone on my phone. Even bad news sounds good when prefaced by that cheery clarinet.

I like the show so much that I am replacing my glass of water on a Diagnosis Murder coaster in between typing sentences (yes, I have four. And they were a Valentine's gift. Envy me). I like it so much that I have a signed photo over my desk of Dick Van Dyke in his Diagnosis Murder doctor's coat, holding a skull quizzically. It says, "Hi Natalie! God bless, Dick Van Dyke" and if there were a fire I can honestly say I would get it before I made sure all the living people were out of the building.

Everything in Diagnosis Murder is perfect. Dick Van Dyke is Dr Mark Sloan, healer of the sick, solver of crimes, and eventually co-owner of BBQ Bob's – a fast food restaurant jointly owned by his son, Lt Steve Sloan, and his teeny medical chum, Dr Jesse Travis, where violent crime is unusually well represented. Dick first played the role in the crime show, Jake and the Fatman, before all right-minded people everywhere realised he needed his own show, and eight seasons of it.

Steve Sloan is played by DVD's real-life son, Barry Van Dyke, on whose jaw you could easily slice cheese. And don't think that's the only other Van Dyke in the show, either, because all four of Barry's kids turn up at one time or another, as does Dick's daughter, Stacy, and his brother, Jerry. The final episode (The Blair Nurse Project, 8,22), features six Van Dykes. Which was surely enough for a musical – a wasted opportunity for which I routinely pine.

They're accompanied in crime-solving by Dr Amanda Bentley, forensic pathologist, and either Dr Jack Stewart in the first two seasons (Scott Baio), or Dr Jesse Travis (Charlie Schlatter) in the rest. Jack is a kid from the wrong side of the tracks made good, who can leap from an exploding building with such panache that this stunt is known in my flat as "a Baio". But my heart belongs to Jesse, who is sweetly funny, clever yet hapless, and has Robert Culp as his super-spy dad.

Meanwhile, Amanda is played by superwoman Victoria Rowell, who somehow managed to have major roles in two shows at the same time (Diagnosis Murder and The Young and the Restless), and still never looked like she couldn't remember which one she was doing that day. Even when Diagnosis Murder had a crossover episode with The Young and the Restless (Death in the Daytime: 2, 21).

The Diagnosis Murder writing team were always unafraid to use DVD's range. He plays five characters in one episode (Inheritance of Death, 1, 4), including one who has a perfect English accent. This proves, to my mind conclusively, that in Mary Poppins, he was taking the piss. And the pull of DVD is such that they can get guest stars en masse that other shows could only dream of: Drill for Death (5,15), for example, includes Elliott Gould and Sally Kellerman from the film version of M*A*S*H and Loretta Swit, Jamie Farr and William Christopher from the TV series. It's the only time the two Hot Lipses ever appeared together. And perhaps the only time an artist was murdered for not being dead already.

Also, who could forget Alienated (6,6), in which Jesse is tricked by Big Pharma into believing in alien abductions? They managed to persuade George Takei, Walter Koenig, Grace Lee Whitney and the late Majel Barrett (that's Mrs Gene Roddenberry to you) from Star Trek to guest star, along with Wil Wheaton from Star Trek: The Next Generation, and Bill Mumy from The Twilight Zone. That is some high-end geekery. And did I mention that Jack Klugman guest stars as two different characters, one of them obsessed with catching The Clown Killer? Take that, Quincy, ME.

DVD is not just a global treasure, he's a multi-skilled one. In early episodes, Mark Sloan is frequently seen roller-skating, even though DVD is slightly older than the queen, and everyone says how great she is for her age when she never roller-skates, or if she does, it's certainly not on film. In one episode, he interrogates a suspect while tap-dancing (Flashdance with Death, 1,11). And don't even start me on his occasional singing with a barbershop quartet or I will cry with joy.

Iconic? Can you even ask? Yes, yes, yes.

Duffers? Don't be ridiculous. The very idea. The only thing wrong with Diagnosis Murder is that only the first three seasons are available on DVD. Why do they torment me? Please write in and help redress this travesty